Drill steel centralizer



Jan. 12, 1943. M. OFARRELL DRILL STEEL CENTRALIZER Filed July 2, 1940 2 Sheets-Sheet l INVENTORQ J/i/flefl dFiz-refl A, 7% ATTORNEY.

an. 12, 1943. .MIUFARRELL 2,308,203

DRILL STEEL CENTRALI ZER Filed July 2, 1940 2 Sheets-Sheet 2 ATTORNEY.

Patented Jan. 12, 1943 DRILL STEEL OENTRALIZER vMatthew OFarrell, Detroit, Mich, assignor to i Chicago Pneumatic Tool Company, New York,

N. Y., a corporation of New Jersey Application July 2, 1940, Serial No. 343,526

'1 Claim.

This invention relates generally to drill steel centralizers and more particularly to device of this class having guide arms which are settable into and out of guiding position and yieldingly held in each position.

A centralizer of this class is generally constructed for use with rock drills of the drifter type. The centralizer functions to maintain the steel in axial alignment with the drill when spotting or starting holes in irregular surfaces, or at an angle, and to prevent the steel from departing from the desired course throughthe rock when the elements of the regular drill steel bearing become worn. In order that the drill may be fed out to its full capacity the guiding element or elements for the steel are rocked out of guiding position by the front head of the advancing drill.

The centralizer of the present invention is broadly similar to those of'the prior art in that it is mounted at the front end of the supporting shell and has a pair of guide arms movable into and out of guiding position with respect to the drill steel at a point between the free end of the steel and the front head of the drill. By this invention, however, certain specific improvements are presented over the prior art including:

1. The combining of the centralizing mechanism and the end plate of the shell mount in a single unitary structure acting as an extension of the shell.

2. The provision of a yielding means adapted to maintain the guide arms in each of a plurality of set positions.

3. A simple and durable mounting for the guide arms which renders unnecessary the frequent replacement of the parts of the mounting.

One object of the invention is to produce a drill steel centralizer of simple and rugged construction which opens on contact with the front head of the drill.

Another object of the invention is to combine the functions of the conventional shell end plate and drill steel centralizer in a unitary structure to be mounted on the shell as an extension thereof.

Another object of the invention is to enable the I guide arms of the centralizer to be yieldingly held in each of a plurality of set positions.

Another object of the invention is to improve the pivotal action of the guide arms and reduce the wearing effect of such action through the provision of a novel guide arm mounting.

Other objects and structural details of the invention will be more apparent from the following description when read in conjunctio n with the accompanying drawings, wherein:

Fig. 1 is a plan View of a centralizer unit showing one form of the invention; Fig. 2 is a View in side elevation of the centralizer unit shown in Fig. l;

Fig. 3 is a view in front elevation of the cen tralizer unit shown in Fig. 1, with the mounting for one guide arm shown in cross section Fig. 4 is-a detail view, in section, 'ofthe guide arms and associated yielding retaining means shown in Fig. 1, and is'taken substantially along the line 4-4 of Fig. 3;

r Fig. 5 is a view in cross section through the midportion of the centralizer unit, and is taken along the line 5-5 of Fig.2;

Fig. 6 is a detail view, inperspective, of the spring pressed plunger that engageseach guide It .will be seen that the centralizer comprises,

generally, a frame piece, or support I6 and a pair of guide arms I I supported by the frame piece Ill. The frame piece In is formed with a head portion I2, a neck I3 (see Fig. 5) and a shouldered portion or face plate I4 by which the frame is secured to the front of the guide shell. The face plate I4 is formed with suitable openings to receive the adjacent ends of the usual supporting rod I5, of the shell, and is fastened to the rods by nuts I6. A projecting portion I! of the frame extends beyond the face plate I 4 and is formed with a recess I8 into which the reduced front end of the feed screw I9 extends. The frame piece It] is thus an extension of the conventional shell and, in functioning as a bearing for the feed screw l9 and end piece for the rods I5, replaces the usual end plate of the shell.

The frame piece IE3, when mounted on the shell, emends forwardly and underlies the front end of the rock drill 21 (Fig. 2) and the drill steel 22. The rock drill 2! is mounted in a manner not shown upon the shell and, by rotation of the feed screw I9, is caused to move relatively to the shell to advance and retract the drill steel through the rock. The centralizer guide arms II extend inwardly and upwardly from respective pivot points on opposite sides of the frame piece I0 and the outer end of each arm is formed with a concave surface 23 (Fig. 3) which encircles a portion of the drill steel 22. Through the cooperation of the pair of arms II the drill steel is positively held against deviation from its axial movement. The arms II, when set in cooperative relation with the steel 22, lie in the path of the front head of the drill. Therefore, in order that the drill may be fed out to its full capacity the arms H are given a pivotal mounting so that they may be rocked out of effective position by the advanci-ng drill.

The inner end of each arm l l is positioned in an angled slot 24 cut in an upstanding portion 25 of. the frame piece H1. The upstanding portions 25 are formed at the front of the frame ill, on oppo site sides thereof, and give a U-shaped appearance to the frame, when viewedinffofit elevation to be engaged by the plunger 28 and the guide arms are so held from movement until a positive force acts on the arms to displace them. The application of such a force by the drill 2|, as it nears its most advanced forward position, serves to rock the guide arms outward or downward as viewed in Fig. 4, to the positions shown in dotdash outline therein. Thismovement of the guide arms 'll places them out of cooperative relation with the drill steel 22 and out of the path of.the drill 2|, and brings the engaging surfaces 33 into position opposite the plungers 28. The guide arms willsthen be held in ineffective position and as a fulcrum about which the guide arm. rock Suitable locking nuts are provided to holdthe h bolts 26,111 place, and a spacing ring 2 1;(seealso Fig. 4) is positionedin each slot 24 to preventthe jaws which form the slotfrom being compressed to a po sition in whichthey might hinder move ment of theguide arms I I, 'The ingsTl surround H the bolts 2 6 and serve the additional function of acting. as bearings for the arms I l. The bolts 26 are'thusnotwqrn by operation of the guide arms I I and do not require frequent replacement.

Referring to Figs. 4, 6 and 7 the means for yieldinglyholding the guide arms in the positions towhich they are set resides in a pair of plungers 28, one of which is, mounted in each of the upstanding portions 25 of the frame [0 in a positionat substantially rightangles to the associated guide arm I l. The plungers 28 are pressed by means of spri l s 23 into the slots 24. where the enlarged .heads'3 l, thereof, engage the respective inner ends of the guide arms H. The inner end of each arm ll isformed with a pair of flat enagingsurfaces 32 and 33 (Fig. 4 which lie adjacenttheheadjil ,of plunger 28 and at an angle,

' somewhat greater than 90 degrees, with respect to each other. With the guide arms in cooperative relation with the drill steel 22, as shown in Figs. 3. and .4; the'surface 32 .of each arm is in position.

must be restored. manually to guiding position upon lli l' hqrajialfqfifthe drill from advanced position.

To facilitate the rocking movement of the guide armslthepointfll between the surfaces 32 and 33 is rounded.

For assembly purposes each plunger 28 is formed with a ho1e..3.5:ne.ar its oute'nend. When assembling the guide. ,arms,ll, theplungers 28 are pressed outward ;until the. holes. 35 .lieo'utside the plunger housing- Pins ..or..n ails maythen-be inserted in the holes to hold-the.springs 29.com pressed until the guide .arms have. be'en.bolted:in place. Openings, 35, communicating with. the plunger. chambers. in the .portions .2 5;. are..for the purpose of allowing any. dirt... or. foreign matter which might. enter. the plunger chambers .todrop out. e

What is claimed is:

A drill steel .centralizer .comprisinga fixedsupport formed with separatesetsotjaws, apivot bolt. passed transversely Lthrough .ea'chlof said sets of jaws. guide. arms .each .having .one .endpositionjed Wit r spective. set. of .jawssandli mounted ona pivot bolt therein for pivotal movement relative to, saidfixed support, andia bushing surrounding each of said-pivotbolts and-interposed-:between the, associatedlset of..jaws,.said bushingserving as a.frictionbearing.between-said bolt -and guide arm and .asawedg'e betweensaid jaws to prevent compression .of .theljaws into binding engagement withthe guide.arm.

' OFARRELL new 

